Bradabyssa verrucosa Salazar-Vallejo 2017, n. comb.

Bradabyssa verrucosa (Chamberlin, 1919) n. comb.

Figure 30

Brada verrucosa Chamberlin, 1919: 399 –400, Pl. 68, Figs 3–6.—Fauchald 1972: 217.

Type material. Eastern Pacific Ocean. Western Mexico. Holotype of Brada verrucosa (USNM 19341), three paratypes (USNM 19342), and five paratypes (MCZ 2373, labelled as syntypes, but Chamberlin handwritten tag records them as paratypes), R.V. Albatross, Tropical Pacific Expedition, Sta. 3417 (16°32' N, 99°48' W), 902 m, 11 April 1891 (three complete paratypes (USNM 19342) 42–60 mm long, 4.0– 5.5 mm wide, no cephalic chaetae, 52–53 chaetigers; complete paratypes (MCZ 2373) 32.5–65.0 mm long, 3.7–6.0 mm wide, no cephalic chaetae, 49–52 chaetigers).

Additional material. Gulf of California. One specimen (LACM 9551), broken into two, damaged, probably fixed in alcohol, anteroventrally dissected, mouth of Gulf of California, Sta. P 91-59 (23°54.7' N, 108°09.5' W → 23°53.6’ N, 108°08.1’ W), 723–741 m, R.H. Parker, coll. (55 (15+40) mm long, 5 mm wide, cephalic cage 18 mm long, 46 (8+38) chaetigers). Two specimens (UNAM 7891), one complete, R.V. El Puma, Cruise Talud V, Sta. 3 (21°59' N, 106°29' W), modified Karling Dredge, 732 m, 13 Dec. 2000 (complete 47 mm long, 3 mm wide, cephalic cage 8 mm long, 49 chaetigers; larger specimen 70 mm long, 6 mm wide, cephalic cage 15 mm long, 25 chaetigers; gonopodial lobes in chaetiger 5).

Description. Holotype of Brada verrucosa (USNM 19341) complete, partly dehydrated; some paratypes better preserved; holotype (Fig. 30C) body dark brown, cylindrical, tapered, posteriorly swollen; 74 mm long, 6.5 mm wide, cephalic cage chaetae broken, 50 chaetigers. Tunic papillated, tubercles alternate in size and position, mostly large, thick, slightly compressed (Fig. 30A, C), capitate, covered by sediment, arranged in 3–4 transverse series. Posterior segments with transverse series of large tubercles.

Anterior end not modified; holotype not dissected, observed in a non-type specimen (MNHN 186a). One with anterior end exposed. Cephalic hood reduced, covered by branchial plate. Prostomium low pale cone, without eyes. Caruncle elongated, separating branchial plate into two lateral groups (Fig. 30B). Palps short, palp keels rounded, well developed. Lips damaged during dissection.

Branchiae sessile on branchial plate, cirriform, about 100 filaments per side. Nephridial lobes positioned ventrolaterally to branchial plate.

Cephalic cage chaetae missing in most specimens (LACM 9551 with very long chaetae; over three times longer than body width). Only chaetiger 1 involved in cephalic cage (in LACM 9551 first 3 chaetigers with long chaetae over three times longer than body width); chaetae arranged in short dorsolateral series, 3–5 chaetae per ramus.

Anterior dorsal margin of first chaetiger papillated, papillae tiny. Chaetigers 1–3 of similar length; second parapodia largest (parapodial lobes projected in several specimens); third parapodia smaller. Chaetal transition from cephalic cage to body chaetae abrupt; aristate neurospines present from chaetiger 2. Gonopodial lobes in chaetiger 5 (Fig. 30C).

Parapodia abraded in holotype, apparently poorly developed, short conical lobes; one paratype with some parapodia slightly damaged (Fig. 30D), notopodia well developed, chaetae emerge between two bottle-shaped papillae, one prechaetal, one postchaetal. Second parapodia largest, third smaller. In paratypes parapodia lateral; median neuropodia ventrolateral. Notopodia and neuropodia close to each other. Notopodia slightly developed; neuropodia much larger than notopodia, most papillae eroded.

Median notochaetae arranged in tufts, all multiarticulate capillaries, short articles basally, medium-sized medially, long distally (Fig. 30E); 2–3 notochaetae per fascicle, as long as 1/3 body width. Neurochaetae thicker, all missing in holotype, but bases arranged in horizontal C-shaped pattern, 5–7 per bundle, in posterior chaetigers in Èshaped pattern. Few aristate spines in some paratypes, aristae mostly lost, few remain (Fig. 30D, inset).

Posterior region tapered, posterior end swollen, pygidium blunt conical, anus dorso-terminal, anal cirri absent.

Remarks. Bradabyssa verrucosa (Chamberlin, 1919) n. comb. belongs in the group of species having dorsal papillae of two markedly different sizes; it differs from other species in the group because there are only 3–4 series of dorsal tubercles per segment and its larger tubercles are distinct, often covered by pigmented sediment particles.

Chamberlin (1919, Pl. 68, Figs. 3–6) inverted the labels for the figures so what he indicated as a neurochaeta (his Fig. 4) is a notochaeta, and what he indicated as notochaeta (his Fig. 5) corresponds to a neurochaeta.

Fauchald (1972:217) stated that there were no notopodia in the last 10–15 chaetigers, and that papillae were soft, not hard, as originally described. However, the holotype has both notopodia and notochaetae almost to the end of body; up to chaetiger 48 there is only a broken basis of a single chaeta. Furthermore, papillae are covered by a thick layer of fine sediment, rendering it hard, but this sediment breaks off easily and papillae are soft.

The Gulf of California specimen (LACM 9551) is remarkable in several aspects. It has very long chaetae in chaetigers 1–3 and its body is very soft. It may have been fixed with ethanol, because the larger dorsal papillae are dehydrated and some even have a median fracture, transverse to the body axis. The long chaetae may be related to reproduction although epitoky or swarming behavior has not been documented for any species in the genus.

Distribution. Eastern Pacific Ocean, Gulf of California and off western Mexico, in about 1000 m water depth.